week 10 Flashcards
Pelvic girdle
Hip bones ± sacrum
Orientating the Pelvis
ASIS and pubic tubercles line up in same coronal plane
* Inferior tip sacrum/base of coccyx lies just superior to pubic symphysis in transverse plane
* R & L ASIS line up in transverse plane
* Acetabulum is directed inferolaterally 4
Functions of the Pelvis
1) Support and protect pelvic viscera (organ)
2) Provides bony support for the birth canal/ an exist foe foetus
3) Provides extensive muscle attachment sites
4) Supports the weight of the head, trunk and upper limbs
5) Allows for weight transfer
* from trunk to lower limb
* Standing – weight to femurs
* Seated – weight to ischial tuberosities
what forms the pelvic inlet
Pubic crest
* Pectineal line
* Arcuate line
* Sacral alar & promontory
- False or greater pelvis
- Superior to pelvic inlet
what forms part of the pelvic outlet
- Apex of coccyx
- Ischial tuberosities
- Pubic symphysis (inferior edge)
- True or lesser pelvis
- Inferior to pelvic inlet
Pubic Symphysis – Secondary Cartilaginous Joint
Between the symphyseal surfaces of pubic bones
* Fibrocartilage disc
* Supported by ligaments
* Limited movement
* exception is in pregnancy
* the fibres soften
* Relaxin hormone
* Osteitis pubis
Sacroiliac Joint Classification
- Anteriorly
- Synovial
- Plane joint
- Non-axial
- Posteriorly
- Fibrous joint
- Due to massive interosseus ligaments
articular surfaces of sacroiliac joint
auricular surface of the ilium
* auricular surface of the sacrum
* fibrous part= Tuberosities for fibrous part of the joint
Sacroiliac Ligaments – Anterior
Anterior sacroiliac ligament
* Iliolumbar ligament
* Interosseus Sacroiliac ligament
Sacroiliac Ligaments – Posterior
- Posterior/dorsal sacroiliac ligament
- Long & short fibres
- Sacrotuberous ligament
- Sacrospinous ligament
Weight Transfer through the Pelvis
- Sacrum is suspended between innominate bones
- Weight pushes the sacrum inferiorly
- Sacrum becomes ‘wedged’ in
- Irregular joint surfaces interlock
- Ligaments come under tension
- Ligament attachments mean the ilia are pulled towards the sacrum
- The sacroiliac joint self-locks
Sacroiliac Joint Movements
- Due to forces
- Not due to muscles
- Movements
- Small amounts of
- Gliding
- Rotation
- Nutation
- Anterior rotation of superior sacrum
- Counter-nutation
- Anterior rotation of inferior sacrum
- Nutation is resisted by
- Sacrotuberous ligament
- Sacrospinous ligament
form closure
describes the stability of the joint/from pelvic anatomy design (passive structures)
- Joint surface configuration - ridged, interlocking surfaces
- Joint surface alignment relative to gravity and bodyweight - “keystone-like” shape
- Tension in the restraining ligaments associated with normal alignment of the segments
force closures
s the term used to describe the other forces acting across pelvic joints to create stability (active structures including fascia)
- Force (active structures):
- Refers to the interaction of multiple muscle groups
- Act across the joint to enhance compression on the joint surfaces
- This assists in joint stability
- Is the so-called active myofascial oblique sling system
when does nutation occur
- when the sacrum absorbs shock
- The sacrum moves down, anteriorly (superior sacrum)
- As the superior sacrum moves anteriorly and inferiorly, the coccyx moves posteriorly relative to the ilium
- This motion is opposed by the wedge shape of the sacrum, the ridges and depression of the articular surfaces
- The integrity of the posterior, interosseous, sacrospinous, and sacrotuberous ligaments that are also supported by muscles that insert into the ligaments
when does counter nutation occur
the bodys response, lifting the joint up against gravity
* Occurs when the inferior sacrum moves up anteriorly
* This motion is opposed by the posterior sacroiliac ligament that is supported by the multifidus
pelvic drop produced by
psilateral gluteus medius contralateral EO / IO contralateral hip adductors
pelvic drop controlled by
contralateral gluteus medius ipsilateral EO / IO ipsilateral hip adductors
pelvic lift produced by
contralateral gluteus medius ipsilateral EO / IO ipsilateral hip adductors
pelvic lift controlled by
ipsilateral gluteus medius contralateral EO / IO contralateral hip adductors
